Here are some great resources to prepare for Meet the Firms.

https://www.pwc.com/us/en/careers/entry-level.html

https://www.ey.com/en_us/careers/interview-tips

https://www2.deloitte.com/us/en/pages/careers/articles/join-deloitte-recruiting-tips-video-interview-insights.html

https://us-jobs.kpmg.com/careers/WhyKpmg

https://www.vault.com/blogs/interviewing/22-behavioral-interview-questions-big-4-firms-are-asking-now